Potentiometers having resistance elements along which a wiper is moved to provide a voltage output are well known. Nonlinear potentiometers are those in which the voltage output varies nonlinearly as the wiper is moved from an end termination. Nonlinear potentiometers can be used to develop various curves at the output. One of the major undesirable aspects of curve fitting to the use of nonlinear potentiometers is that for the most part the nonlinear function is provided in the potentiometer unit in advance and little or no flexibility is available for varying this.
There are frequent applications where two bias configurations are desirable such as in cable television where it is necessary to set a number of preset voltages for channel selection with a tuner between two fixed biases. There is a requirement for a number of voltages to represent a number of channels. Presently a high resolution pot is used for each channel and no single potentiometer has been available. Additionally there are applications where a more general function between two fixed bias voltages must be generated to satisfy manufacturing tolerances over a range.